Fire screen



Examiner 3 i 106. cuMPusmoNs, -msg Herence COATING 0R PLASUC April 14, 1942. c. G. Uma

FIRE SCREEN Fied Dec. 9, 1939 DUDDIHUDD DUDDDDUDD BIDDBDUD DUBDDDD DDDDDDDDDBBD DDDDDDUDDDDD DDDUDDDDDDD DUDBBDDUUD onbnsnoosaoagoo .....UUDUOGDQ 106. COMPOSITIONS,

COATING R PL AST'C sists of a material or composition embodied in a Cross Reference reticulated or foraminous structure through l,

which air at ordinary temperatures may normally ow and which when activated by subjection to a relatively high temperature will expand so as to close or substantially close the passages or The frothy, permanent obstruction to the passage of air and flame through the screen aoxded when the screen coating has been heat activated is designated on Fig. 2 by reference character I8.

In Fig. 3, I have illustrated a double air iilter consisting of a section I9 having relatively large passages and a section 2| having relatively small passages, the lter being protected on the front side by a screen 22 and on the rear by a screen 23, both of the general character of that ;illustrated in Fig. 2 and by which the lter is adequately protected against combustion or charring. Heat dissipating grids are also preferably employed. 16

, .-In Fig. 4 a screen designated 24 of the character heretofore described is shown as interposed in a Ventilating opening in a fire wall 25. The

openings through the screen and form a per manent non-innammable obstruction to the passage of ame and excessively hot air.

As illustrated in Fig. 2, the screen comprises a foraminous body or frame work I4 of network construction such as a wire screen, for instance, mounted in a metal frame I5. The reticulated body is coated by dipping or otherwise with a composition or material applied to the body lin such a viscous condition that a coating I6 of substantial thickness is imposed upon the individual wires. Ihe spacing of the wires is such that when thus coated, openings I1 of substantial size are left through which air at the normal temperature may freely flow.

While my invention contemplates the employment of various materials or compositions possessing the requisite characteristic of substantial expansion upon subjection to heat, I have found that a composition very suitable for the purpose is afforded by silicate of soda in liquid form with which is admixed a saturated solution of sodium bicarbonate. The preferred although not the necessary proportions are:

Percent Silicate of soda 95 Sodium bicarbonate 5 'I'his solution is applied to the screen body by dipping or otherwise and forms a coating over the wires of varying thicknesses dependent upon the viscosity of the solution when applied. The coarser the screen, the more viscous the solution would be. The applied coating quickly hardens and forms a permanent coating over the wires leaving unobstructed openings between the wires for the passage of air therethrough. A screen thus made may be used in various places as hereinafter indicated, and if employed, for instance, in front of an air filter, as exemplied in Fig. l, will permit a substantially unobstructed flow of air at normal temperatures through the conduit and through the lter.

Upon occurrence of a fire, however, the coating of the screen will, when subjected to a temperature not greatly in excess of 212 F., expand into tenacious bubbles forming a froth which lls, obstructs, and closes olf the openings through the screen, and by reason of the hardness and permanent character of the obstructing froth thus provided, the screen becomes in effect a reproof damper, which automatically shuts off the ow of air therethrough and precludes the passage of flame and the transmission of combustion. 'I'he frothy, imperforate and perm-anent screen thus provided is in itself non-inamrnabie so that it serves as an excellent fire screen to prevent the passage therethrough of flame or dangerously high-temperatured air.

use of a'screen in such a wall permits the ventllation of spaces or compartments such as paint spray rooms, for instance, where the lire hazard is great without reducing the margin of safety. Upon the occurrence of re either inside or outside the space, the normally reticulated screen will be heat activated into the formation of an impervious. non-inflammable screen which will preclude the passage of name or excessively h ot air therethrough.

4In Fig. 5, I have illustrated a screen, the body 26 of which is formed entirely of the material adapted to be heat activated, as previously described. In this instance, the material instead of being applied as a coating to a metal or similar reticulated body is itself molded or otherwise formed to provide a reticulated screen body which when heat activated will be converted into an imperforate, non-innammable screen.

In Fig. 6 the reticulated body 2l of the screen is formed of perforated sheet metal coated with the non-inammable heat sensitive composition adapted when heat activated to close the openings through the screen.

In Fig. 'I the body 28 of the screen is formed of expanded metal to which the heat sensitive material is applied as a coating thereover.

It will be apparent from the foregoing that I have provided a screen which under normal temperature conditions is of a foraminous character permitting a free ow of air therethrough for ventilation or other purposes, but which when subjected to temperatures approaching or exceeding the combustion point will become automatically converted into an impervious, non-inammable screen adapted to prevent the passage of flame or excessively hot air therethrough and thereby preclude the transmission of ,a conagration.

The structural characteristics of the screen body as well as the composition of the Aheat sensitive material of the screen may be varied within .considerable limits without departing from the scope of my invention as defined in the following claims.

I claim: 1

1. A flre screen comprising a perforate body coated with a composition of sodium silicate and sodium bicarbonate adapted upon subjection to heat to produce a foam of substantial permanency closing the perforations of said body.

2. A normally perforate fire screen carrying a I solid solution of sodium silicate and sodium bicarbonate adapted upon subjection to heat to expand and close the perforations'in said screen, thereby rendering said screen impervious to the passage of ame therethrough.

3. A non-inflammable :dre screen comprising Examiner a reticulated body, a frame surronding said body, and a coating consisting of 95%V sodium silicate and 5% sodium bicarbonate applied to the surfaces of said body.

4. The combination with an air lter of a protecting screen therefor including a heat sensit1ve material including a substantial portion of sodium silicate adapted to render said screen imperforate upon subjection to excessive temperatures, and a heat dissipating grid interposed between said lter and said screen.

5. The combination with a combustible air lter of an incombustible, reticulated re screen including a heat sensitive material comprising a substantial portion of sodium silicate adapted upon subjection to heat to render said screen imperforate, and a heat dissipating grid interposed between asid screen and said lter.A

6. A foraminated, non-inammable re screen having a perforated body comprising a material including a substantial proportion of sodium silicate, solid at normal temperatures but expansible at high temperatures to close said perforations and thereby obstruct the pasasge of fiame through said screen.

7. In a device of the character described, a supporting structure of sufficient area to close a passageway, said structure being perforate and having its perforations of predetermined crosssectional area, and a non-infiammable coating of material including a substantial portion of sodium silicate, said material being highly expansible upon subjection to abnormal heat and coating the peripheral portions of the perforations, the extent of expansion of said coating upon subjection to predetermined temperature increase being so related to said area of said perforations that said coating will, upon such subjection, expand sufficiently to close said perfQrations.

CHARLES G. LAMB. 

